From 56abbf8ad73c89d0a4c3c84b1449ceaaabd1b8c7 Mon Sep 17 00:00:00 2001
From: Oza Pawandeep <poza@codeaurora.org>
Date: Wed, 16 May 2018 15:59:35 -0500
Subject: [PATCH] PCI/DPC: Clear interrupt status in interrupt handler top half
Git-commit: 56abbf8ad73c89d0a4c3c84b1449ceaaabd1b8c7
Patch-mainline: v4.18-rc1
References: FATE#326277
The generic IRQ handling code ensures that an interrupt handler runs with
its interrupt masked or disabled. If the interrupt is level-triggered, the
interrupt handler must tell its device to stop asserting the interrupt
before returning. If it doesn't, we will immediately take the interrupt
again when the handler returns and the generic code unmasks the interrupt.
The driver doesn't know whether its interrupt is edge- or level-triggered,
so it must clear its interrupt source directly in its interrupt handler.
Previously we cleared the DPC interrupt status in the bottom half, i.e., in
deferred work, which can cause an interrupt storm if the DPC interrupt
happens to be level-triggered, e.g., if we're using INTx instead of MSI.
Clear the DPC interrupt status bit in the interrupt handler, not in the
deferred work.
Signed-off-by: Oza Pawandeep <poza@codeaurora.org>
[bhelgaas: changelog]
Signed-off-by: Bjorn Helgaas <helgaas@kernel.org>
Reviewed-by: Keith Busch <keith.busch@intel.com>
Acked-by: Takashi Iwai <tiwai@suse.de>
---
drivers/pci/pcie/dpc.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/drivers/pci/pcie/dpc.c b/drivers/pci/pcie/dpc.c
index 8c57d607e603..74562dbacbf1 100644
--- a/drivers/pci/pcie/dpc.c
+++ b/drivers/pci/pcie/dpc.c
@@ -113,7 +113,7 @@ static void dpc_work(struct work_struct *work)
}
pci_write_config_word(pdev, cap + PCI_EXP_DPC_STATUS,
- PCI_EXP_DPC_STATUS_TRIGGER | PCI_EXP_DPC_STATUS_INTERRUPT);
+ PCI_EXP_DPC_STATUS_TRIGGER);
pci_read_config_word(pdev, cap + PCI_EXP_DPC_CTL, &ctl);
pci_write_config_word(pdev, cap + PCI_EXP_DPC_CTL,
@@ -223,6 +223,9 @@ static irqreturn_t dpc_irq(int irq, void *context)
if (dpc->rp_extensions && reason == 3 && ext_reason == 0)
dpc_process_rp_pio_error(dpc);
+ pci_write_config_word(pdev, cap + PCI_EXP_DPC_STATUS,
+ PCI_EXP_DPC_STATUS_INTERRUPT);
+
schedule_work(&dpc->work);
return IRQ_HANDLED;
--
2.19.2